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Physical Review

The Nature of the Iodine Line 2062a

Louis A. Turner, Karl Taylor Compton

Published Jun 1, 1925• 4 citations
Publisher

Abstract

Dissociated iodine vapor at 1100\ifmmode^\circ\else\textdegree\fi{} to 1500\ifmmode^\circ\else\textdegree\fi{}C in a quartz tube failed to show any resonance fluorescence of the 2062 line in a 78 minute exposure in the same apparatus in which mercury vapor gave a detectable fluorescence of the 2537 line in a 1 second exposure. This fact and the narrowness of the 2062 line in absorption, seem to indicate that the lower level involved in the transition producing this line is not the normal state of the atom but is a slightly higher one. A calculation based on the observed line width shows that this level is probably at least 0.545 volt above the normal level and suggests that there may be a resonance line of atomic iodine at about 1800A.

DOI
10.1103/physrev.25.791

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The Metastable 2 p 3 -State of Mercury Atoms

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Let us consider a mixture of mercury vapor, thallium vapor and nitrogen in a closed quartz tube under well defined conditions of pressure and temperature, illuminated by λ 2537A of constant intensity. \n \nDue to the absorption of the illuminating radiation a constant number N of mercury atoms will be activated in unit time. Those activated atoms persist in the 2p2-state for a finite time t which is known to be of the order of magnitude of 10^-7 sec [1]. If they escape collision during this period they return to their normal state in the ordinary wave-emitting radiation (resonance). They may, however, while activated, collide with nitrogen molecules, normal mercury atoms or normal thallium atoms. We shall assume, for the present, that the amount of nitrogen and thallium sufficiently exceeds the amount of mercury, so that we may disregard totally the collisions between activated and normal mercury atoms. \n \nWe assume furthermore that all collisions between activated mercury atoms and thallium atoms result in the activation of the latter, producing the fluorescence radiation of thallium with a constant energy distribution between its different lines.

Proceedings of the National Academy of Sciences•Nov 1, 1925•3 citations

Fluorescent excitation of mercury by the resonance frequency and by lower frequencies. Further studies

Robert John Strutt

Abstract In a previous paper on this subject I examined in some detail the fluorescence excited by the atomic resonance line 2537, and by frequencies lower than this, which act by absorption in the region of longer wave-length than 2537. The fact that this absorption-region is immediately juxtaposed to the atomic line, and that the absorption is (at any rate on a rough view) stronger the nearer we go to the line, makes the distinction between the two cases difficult ; and it must be admitted that the phenomena themselves are not at first sight so distinctive as might be expected, if we take the obvious view that in one case absorption is by atoms and in the other by molecules. This has led some writers to the opinion that atomic absorption does not act at all in giving rise to band-fluorescence. It was shown, however, in the communication mentioned that a discontinuity of intensity in the fluorescence can be observed as the exciting beam traverses the vapour, and is robbed of its more absorbable component. The initial fluorescence due to the core of the resonance line is referred to as the “core effect,” and the much weaker fluorescence distinguishable after the core effect has died out is called the “wing effect,” because it is excited by the wing, or outer region, of the line. With dense vapour, however, excitation can be observed more than 1000 A. to the long wave side of the line, and the term “wing effect” is extended to the whole of this region, because no reason has been found for restricting it. It was found (loc. cit., p. 9) that the core effect is cut out by a supplementary absorption cell of mercury vapour producing a reversal of the line only 0.1 A. in breadth. I wish now to emphasise that this reversal agrees exactly in position with the narrow atomic emission line from a cold source within less than this amount.

Proceedings of the Royal Society of London Series A Containing Papers of a Mathematical and Physical Character•Aug 1, 1931•5 citations

The Sensitized Fluorescence of Potassium

Ernst H. Krause

A mixture of potassium vapor and mercury vapor contained in a tube fashioned after the Cario-Lochte-Holtgreven sodium vapor lamp was radiated by light from a water-cooled mercury arc. The resulting fluorescence radiation contained potassium lines as well as two of the three known ${\mathrm{K}}_{2}$ absorption bands and a new band with maximum at 5721A. On exposure of the mixture to light from a hot mercury arc or to light having all wave-lengths shorter than 2800A filtered out, the fluorescence was eliminated. This indicated that the excitation was caused by absorption of 2536A by the mercury. Absorption of the 2536A mercury line raises the mercury atom to the $6^{3}P_{1}$ state, having an energy of 4.86 volts. The ionization potential of potassium is 4.32 volts; thus in a collision of the second kind, the excited mercury atom has enough energy to ionize the potassium atom. There was no evidence of a potassium emission from an energy state in the continuum equal in energy to the Hg $6^{3}P_{1}$ or $6^{3}P_{0}$ states. There were, however, two strong lines in fluorescence which could not be ascribed to the usual K energy levels nor to any probable impurity. To test whether or not ionization of potassium actually takes place, a filament was introduced into the tube to supply electrons. A large increase in intensity of the fluorescence of potassium lines was obtained with the hot filament. It was furthermore found that the intensity increased with filament temperature.

Physical Review•Jan 15, 1939•1 citation

Fluorescent excitation of mercury by the resonance frequency and by lower frequencies.—V

Robert John Strutt

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Absorption and Resonance of the Helium Infrared Lines

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Physical Review•Mar 1, 1932•1 citation

Resonances of subnatural line width in iodine vapor driven by a polychromatic laser light field atλ=515 nm: a proposal

L. F. Vitushkin, S. V. Lazaryuk, S. A. Pulkin +2 more

An initial study of the characteristics of sub-natural line width resonances in iodine elicited by polychromatic laser light has been made. Results of theoretical calculations are presented. Under proper experimental conditions, super-narrow resonances with high contrast ran be expected.>

IEEE Transactions on Instrumentation and Measurement•Apr 1, 1995•1 citation
Dissociated iodine vapor at 1100\ifmmode^\circ\else\textdegree\fi{} to 1500\ifmmode^\circ\else\textdegree\fi{}C in a quartz tube failed to show any resonance fluorescence of the 2062 line in a 78 minute exposure in the same apparatus in which mercury vapor gave a detectable fluorescence of the 2537 line in a 1 second exposure. This fact and the narrowness of the 2062 line in absorption, seem to indicate that the lower level involved in the transition producing this line is not the normal state of the atom but is a slightly higher one. A calculation based on the observed line width shows that this level is probably at least 0.545 volt above the normal level and suggests that there may be a resonance line of atomic iodine at about 1800A.
Let us consider a mixture of mercury vapor, thallium vapor and nitrogen in a closed quartz tube under well defined conditions of pressure and temperature, illuminated by λ 2537A of constant intensity. \n \nDue to the absorption of the illuminating radiation a constant number N of mercury atoms will be activated in unit time. Those activated atoms persist in the 2p2-state for a finite time t which is known to be of the order of magnitude of 10^-7 sec [1]. If they escape collision during this period they return to their normal state in the ordinary wave-emitting radiation (resonance). They may, however, while activated, collide with nitrogen molecules, normal mercury atoms or normal thallium atoms. We shall assume, for the present, that the amount of nitrogen and thallium sufficiently exceeds the amount of mercury, so that we may disregard totally the collisions between activated and normal mercury atoms. \n \nWe assume furthermore that all collisions between activated mercury atoms and thallium atoms result in the activation of the latter, producing the fluorescence radiation of thallium with a constant energy distribution between its different lines.
Abstract In a previous paper on this subject I examined in some detail the fluorescence excited by the atomic resonance line 2537, and by frequencies lower than this, which act by absorption in the region of longer wave-length than 2537. The fact that this absorption-region is immediately juxtaposed to the atomic line, and that the absorption is (at any rate on a rough view) stronger the nearer we go to the line, makes the distinction between the two cases difficult ; and it must be admitted that the phenomena themselves are not at first sight so distinctive as might be expected, if we take the obvious view that in one case absorption is by atoms and in the other by molecules. This has led some writers to the opinion that atomic absorption does not act at all in giving rise to band-fluorescence. It was shown, however, in the communication mentioned that a discontinuity of intensity in the fluorescence can be observed as the exciting beam traverses the vapour, and is robbed of its more absorbable component. The initial fluorescence due to the core of the resonance line is referred to as the “core effect,” and the much weaker fluorescence distinguishable after the core effect has died out is called the “wing effect,” because it is excited by the wing, or outer region, of the line. With dense vapour, however, excitation can be observed more than 1000 A. to the long wave side of the line, and the term “wing effect” is extended to the whole of this region, because no reason has been found for restricting it. It was found (loc. cit., p. 9) that the core effect is cut out by a supplementary absorption cell of mercury vapour producing a reversal of the line only 0.1 A. in breadth. I wish now to emphasise that this reversal agrees exactly in position with the narrow atomic emission line from a cold source within less than this amount.
A mixture of potassium vapor and mercury vapor contained in a tube fashioned after the Cario-Lochte-Holtgreven sodium vapor lamp was radiated by light from a water-cooled mercury arc. The resulting fluorescence radiation contained potassium lines as well as two of the three known K2{\mathrm{K}}_{2}K2​ absorption bands and a new band with maximum at 5721A. On exposure of the mixture to light from a hot mercury arc or to light having all wave-lengths shorter than 2800A filtered out, the fluorescence was eliminated. This indicated that the excitation was caused by absorption of 2536A by the mercury. Absorption of the 2536A mercury line raises the mercury atom to the 63P16^{3}P_{1}63P1​ state, having an energy of 4.86 volts. The ionization potential of potassium is 4.32 volts; thus in a collision of the second kind, the excited mercury atom has enough energy to ionize the potassium atom. There was no evidence of a potassium emission from an energy state in the continuum equal in energy to the Hg 63P16^{3}P_{1}63P1​ or 63P06^{3}P_{0}63P0​ states. There were, however, two strong lines in fluorescence which could not be ascribed to the usual K energy levels nor to any probable impurity. To test whether or not ionization of potassium actually takes place, a filament was introduced into the tube to supply electrons. A large increase in intensity of the fluorescence of potassium lines was obtained with the hot filament. It was furthermore found that the intensity increased with filament temperature.
Abstract It was shown at an early stage of the present workf that the characteristic fluorescence of mercury could be generated by wave-lengths much longer than the resonance line λ 2537; indeed, its excitation was traced as far as λ 3450. It was found also that the primary excitation by atomic absorption (core of the resonance line) could be distinguished from excitation by molecular absorption (wing of the resonance line). Although in the case of the longer waves it appears certain that the excited systems produced in the first instance by absorption are molecules and not atoms, yet it is possible that subsequent dissociation, or excitation by collision might lead to the formation of excited atoms in a secondary way.
The absorption of helium excited at low voltages for its own lines, the $2^{3}S\ensuremath{-}2^{3}P$ at 10830A and the $2^{1}S\ensuremath{-}2^{1}P$ at 20582A, is determined. The percentage absorption of the $2^{3}S\ensuremath{-}2^{3}P$ line increases when either the exciting current or the pressure in the absorbing tube is increased, and also when either the current or the pressure in the source tube is decreased. When the light to be absorbed is taken end on from a Geissler tube source, the percentage absorption is much less than when the light is taken off at right angles to the capillary. The changes with source tube conditions are ascribed to the corresponding variations of the shape and width of the emission line. Observable absorption begins when the exciting voltage is 25 volts. No absorption is detected at 19.8 volts, the excitation potential of the 23S2^{3}S23S state. The 10830A line shows strong resonance which is directly proportional to the percentage absorption. The absorption for the 20582A line is very small. It shows no detectable resonance.